Loom dobby



p 1969 e. PIAZZOLLA ETAL 3,464,451

LOOM DOBBY Filed Jan. 16. 1968 IIIIIIIIIIIIIIIIIIIIL' U.S. Cl. 139-74 Claims ABSCT OF THE DISCLOSURE A dobby for textile looms comprises selector rockers which are independently movable between two end positions. The rockers are biassed to one of the positions. Selecting hooks each cooperate With a baulk lever and are movable between a first and a second position in which the associated bauik lever is respectively displaced in opposite directions. Bach selecting hook has an end portion engaging one of the rockers and is maintained in its first position by such engagernent. Biasing means engages the hooks and urges them towards their second position but is unable to overcome the bias of the respective rockers towards their one end position. Draw knives are each associated With one of the hooks and movable between a withdrawn position and an engaged position in which latter each draw knife displaces the associated hook towards the second position thereof. Each draw knife is further associated With one of the rockers and operable thereby for movernent between its withdrawn and engaged positions. Programming means is operative for sequentially efiecting movement of selected rockers between their rest and operated positions.

This invention reiates to a dobby for looms, and in particular for loorns capable of weaving cloth in band or strip form and of working at high speeds.

Certain types of loom are known, particularly 1ooms for weaving single bands, strips, belts and the like, in which the working speed is limited by the limited working speed of the dobby. Thus the textile industry has sought to design satisfactory high speed dobbies but up ti11 110W it has not been easible to make dobbies capable of running at more than 500 or 600 strokes per minute under the most favourable conditions.

A conventional dobby requires, for the movement Of the heddles, draw knives which are selectively brought into engagement With mobile hooks, the selection being effected by selector rockers moved by programming means, such as perforated paper or cardboard bands or rollers with suitably distributed pins. The connection between the selector rockers and the hooks takes place through upright needles, each disposed between the end portion of a selector rocker and the end portion of a respective hook. The hooks are generally moved by means of cams, which have partiy circular profiies so that the hooks can rernain stationary for a time interval in the cycle and engagernent With the draw knives is facilitated.

The connection between the selector rockers and the hooks by means of needles limits the working speed of the dobby, inasrnuch as above a certain working speed the needles are submitted to vibrations and rebound eiects which hinder the seiection.

According to the invention, there is provided a dobby for textile looms which includes selector rockers operable in accordance With a predetermined programme for selecting hooks for movement by draw knives, in which dobby the rockers are arranged to act on end portions of States Patent 3,464,451 Patented Sept. 2, 1969 the hooks without intermediate operating needles and means are provided to continuously urge the rockers and the hooks one towards the other.

Another feature of the dobby hereinafter described is that the draw knives are operated by means of a connecting rod driven by an eccentric, instead of by a pair of cams.

An exarnple of the invention will now be described With reference to the accompanying drawing in which:

FIG. 1 shows a dobby in verticai eross-section; and

FIG. 2 is a side elevation of the draw knfe operating mechanism of the dobby of FIG. 1.

The dobby, as illustrated in FIGS. 1 and 2, is of the double lift type. In this dobby, two rockers l, suitably spaced, respectiveiy carry upper and lower draw knives 2 and 3. The rockers 1, Wth the draw knives 2 and 3, are mounted for oscillation around a pivot 4, oscillation being effected by means of a connecting rod 5 driven by an eccentrc 6 mounted on a driving shaft 7 (FIG. 2).

A series of upper hooks of which one is shown at 8 is arranged for engagement With the upper draw knife 2, and a series of lower hooks of which one is shown at 9 is arranged for engagernent With the lower draw knife 3.

The upper and lower hooks 8 and 9 which are typical of their respective series and which ho in the same vertical piane, are connected to a baulk 10 capable of pivoting about an upper stop 11 or about a lower stop 12 according to the hook which is engaged by the knife 2 or 3. The bau1k 10 is pivotally mounted on a jack 13 which controls a heddle through a connecting rod (not shown) in the usual manner.

Draw knives 2 and 3 only engage selected hooks, viz: those hooks which are disposed for engagernent by the draw knives.

For the selection of the upper hooks there is provided an upper row of selector rockers of which one is shown at 14. The selector rockers are pivotable about a common pivot 15 and are controlled, through a cam follower surface 14' thereon, by pins 16 on an upper roller 17. For the selection of the lower hooks, there is provided a lower row of selector rockers of which one is shown at 18. These lower selector rockers are pivotable about a common pivot 19 and their oscillation is efected by pins 20 on a lower rolier 21.

The use of two rollers or cylinders 17 and 21 permits substantial simplification of the dobby inasrnuch as it eiiminates or reduces the rebound efects encountered When only one rller or cylinder is employed.

The upper selector rocker 14 has an arm 22 the end of which is bent upwards to support a rolier 23 aganst which the reduced cross-section end 2 of the hook 8 bears.

A second arm 24 of the selector rocker 14 projects downwards and is biased by a tension spring 25 fixed between the arn1 24 and a small shaft 26 extending between the hubs of the levers forming the rocker 1. The spring 25 serves to hold the selector rocker 14 and the hook 8 in contact through the roller 2.3.

Similarly, the lower selector rocker 18 has an arm 27 having a downwardly directed end which bears a roller 28 restng on an end portion of the hook 9. The selector rocker 18 a1so has an upwardly directed ann 29 biased by a tension spring 30 between the arm 29 and a second small shaft 31 extendng between the hubs of the levers forming the rocker 1.

The hooks 8 and 9 are connected by a tension spring 32 which forces the ends of the hooks 8 and 9 against the rollers 23 and 28. However, the sprngs 25 and 30 are such as to overcome the force exerted by the spring 32 so that, when the selector rockers 14 and 18 are in the rest position (i.e. as illustrated in FIG. 1), the hooks 8 and 3 9 are held out of the paths of the respective draw knives 2 and 3.

The operation of the dobby is as follows:

When 21 pin 16 engages the cam follower surface 14' of a respective selector rocker 1 4, it lifts the rear portion of the rocker and lowers the end of the arm 22. The respective hook 8 thus drops under the action of the spring 32 into the path of the draw knife 2. The draw knife 2, due to its forward movernent, carries forward the selected upper hooks, thus rocking the respective baulks 10 about the sop 12. The corresponding jacks 13 are thus displaced about their common mounting shaft 13'.

In a similar manner, a pin 20 can rock the respective selector rocker 18, so lifting the arm 27 thereof. The respective hook 9 Will then be lifted by the spring 32 into the path of the draw knife 3. The draw knife 3, due to its forward movement, Will carry forward the selected iower hooks thus rocking the respective baulks 1G in the opposite direction to that efrected by the upper hooks. The eiect is thus to dispiace the respective jacks 13, or hold them displaced if they are already displaced by the upper hooks.

The illustrated dobby has been found to be relatively free of vibration and shaking, Whiie the direct connection between selector rockers and hooks through the roilers 23 and 28 reduces the friction and consequently also the wear of these members. Also, a high speed of osciliation of the rocker I can be effected through the connecting rod and the eccentric 6. Furthennore, movernent of the hooks by means of springs 32 permits a high speed of selection. As the hooks 8 and 9 move synnnetricaiy, only hooks by means of springs 32 permits a high speed of a single spring 32 is required to effect their movernent.

Another feature of the illustrated dobby is that the draw knives 2 and 3 are moved only by a common pair of rockers 1 in contrast to previously known dobbies, wherein there is used a pair of levers for each draw knife. The illustrated arrangement has the advantage of iimiting the stress upon the dobby, inasmuch as the force necessary to lift the heddles, as a draw knife is moving forward, can be counterbalanced by the weight of he heddles which are being lowered due to the return movernent of the other draw knife.

This illustrated arrangement also permits simpiification and reduction of manufacturing costs.

What we ciaim is:

1. A dobby for textile looms comprising, in combination, a plurality of selector rocker members each independentiy movabie between a normal rest position and an operated position; first biasing means urging said selector rockers to said rest position; a plurality of selecting hook members each cooperating With a baulk lever and movable between a first and a second posiion in which he associated baulk lever s respectiveiy displaced in opposite directions, each of said hook members having an end portion engaging one of said rocker members and each hook being maintained by said engag;ernent in said first position; second biasing means urging said hook members towards said second position counter to said first biasing means; a plurality of draw knives each associated With one of said rocker members and one of said hook members and mounted for movement in responsive to movement of the respective rocker member to operated position from a withdrawn position to an engaged position in which it displaces the associated hook member towards said second position thereof; and programming means operative for sequentially eifecting movement of selected rocker members between said rest and operated positions thereof.

2. A dobby as defineci in claim 1; further comprising connecting rods associated With said draw knives, and eccentric means associated With said conneeting rods and operative for imparting to said connecting rods and thereby to the associated draw knives an oscillatory movement.

3. A dobby as defined in claim I, said first and second biasing means comprising spring means.

4. A dobby as defined in claim 1; further comprising a pluraiity of rollers each interposed betweerr an end portion of one of said hook members and the associated rocker member and being carried by one of said members.

5. A dobby as defined in claim 1, said plurality of hook members and said plurality of rocker members each constituting a first and second series of hook membcrs and associated rocker mernbers, respectively, and said rogramming means including fi;rst and second programming means respectively cooperating With said first and second series of rocker members.

6. A dobby as defined in claim 5, the hook members of said first and second series of hook members being associated and mounted so that movement of a hook member in one of said series to said second position results in automatic movement of the associated hook mernber in the other series to said first position.

7. A dobby as defined in claim 1, said programming means comprising roller means provided With a plurality of circumferentially distributed programming pins.

8. A dobby as claimed in cam 1, wherein the draw knives are moved only by a common pair of said rocker members pivoted in their middle point.

9. A dobby for textile looms comprising, in combination, a plurality of selector rockers each independently movable between a normal rest positon and an operated position; first biasing means urgng said selector rockers to said rest position; a plurality of selecting hooks each cooperating with a baulk lever and movable between a first and a second position in which the associated baulk lever is respectively displaced in opp0site directions, each of said hooks having an end portion engaging one of said rockers and each hook beng maintained by such engagernent in said first position, said plurality of roekers and said plurality of hooks each constituting a first and a second series of rockers and hooks, respectively; second biasing Ineans urging said hooks towards said second position counter to said first biasing means; a plurality of draw knives each associated With one of said rockers and one of said hooks and mounted for movement, in response to movement of the respective rocker to operated pos1tions, from a withdrawn position to an engaged position in which it displaces the associated hook towards said second position thereof; and first and second programming means respectively cooperating With said first and second series of rockers and operative for sequentially eflecting movernent of selected rockers between said rest and operated positions thereof.

10. A dobby for textile looms comprising, in combinatron, a plurality of selector rockers each independently moyzrble between a norma] rest position and an operated posrt1 on; first spring means urging said selector rockers to said rest position; a plurality of selecting hooks each cooperating With a baulk lever and movable between a first and a second position in which the associated baulk lever 1s respectively dispiaced in opposite directions, each of said hooks having an end portion engaging one of said rockers and each hook being maintained by such engagement in said first position, said plurality of rockers and said plurality of hooks each consttuting a first and a second series of rockers and hooks, respectively; second spring means weaker than said first spring means urging said hooks towards said second position co'unter to said first spring means; a plurality of draw knives each associated With one of said rockers and one of said hooks and mounted for movement, in response to movement of the respective rocker to operated positions, from a withdrawn position to an engaged position in which it displaces the associated hook towards said second position thereof; and first and second programming mezms respectiveiy cooperating with said first and second series of rockers and operative for sequentiaily eiecting move- 5 6 ment of selected rockers between said rest and operated 2,071,784 2/1937 Edwards 139-66 positions thereof. 2,705,506 4/1955 Staubli 139-71 References Cited 2,751,938 6/1956 Staubli et al. 139 74 X UNITED STATES PATENTS 3,225,792 12/ 1965 Piazzolla et al 139-71 5 897568 9/1908 139-74 JAMES K. CHI, Primary Examiner 1,052,768 2/1913 Tellier 139-74 

